Distributing valve



NOV. 9 J. L. GLIDDEN ETAL 3,

DISTRIBUTING VALVE Filed July 17, 1964 2 Sheets-Sheet 1 INVEN TORS JAMES L.GLIDDEN ROBERT C. WESTVEEF? ATTORNEYS Nov. 1, 1966 J. 1... GLIDDEN ETAL 3,282,286

DISTRIBUTING VALVE Filed July 17, 1964 2 Sheets-Sheet 2 l2 FIG.4

IN VEN TORS JAMES L.GL|DDEN ROBERT C.WESTVEER ATTORNEYS United States Patent 3,282,286 DISTRIBUTING VALVE James L. Glidden, Toledo, Ohio, and Robert C. Westveer, Kalamazoo, Mich, assignors to TheNew York Air Brake Company, a corporation of New Jersey Filed July 17, 1964, Ser. No. 383,310 3 Claims. (Cl. 137-119) This invention relates to distributing valves for controlling the flow of hydraulic fluid to land from a plurality of rams or cylinders.

Valves of this type are in common use and in general include a housing containing inlet and exhaust ports and a plurality of valving units, each of which is provided with a pair of service ports to which and from which it controls the flow of fluid. The units receive fluid from a supply manifold leading from the inlet port and which may connect them either in series or in parallel, and direct to an exhaust manifold'the fluid being returned to the valve through the service parts.

In some cases, the rams controlled by the distributing valve are subjected to gravitational or inertial loads that cause them to move at a rate faster than that with which the supply pump can keep pace. When this happens, the expanding side of the ram cavitates. It is well known that this condition can be eliminated by providing a bypass path between the opposite sides of the ram which is controlled by a valve that opens automatic-ally whenever the pressure in the expanding. side of the ram decreases to a low level indicative of cavitation. The regenerative flow through the by-pass path supplements the fluid being supplied by the pump and'insures that the expanding side of the ram will be maintained liquid-filled. Some bypass valves are connected between the linesleading from the service ports to the ram, and others are embodied in the movable element of the valving unit itself. While these arrangements are satisfactory from the performance standpoint, they can 'be expensive in installations where more than one ram tends to cavitate because a separate by-pas's valve is required for each ram.

The object of this invention is to provide an improved distributing valve that includes a single regeneration device that services all of the v-alving units. According to the invention, the supply and exhaust manifolds in the housing of the distributing valve are interconnected by a bypass passage controlled by a check valve arranged to open and permit flow to the supply manifold when the pressure differential between the two manifolds reaches a predetermined value. Since the supply manifold delivers fluid to all of the valve units, and a decrease in its pressure is indicative of incipient cavitation, the check valve will-open and initiate regenerative flow when any of the rams controlled by the distributing valve tends to cavitate. Coupled to the check valve is a variable flow restrictor whose degree of restriction increases and decreases, respectively, as the check valve opens and closes. The inclusion'of this flow restrictor permits the pressure in the supply manifold to rise above that in the exhaust port at times when the check valve is open and thus insures that the back-pressure in the exhaust manifold will be adequate to force fluid through the line leading from the service port to the expanding side of the cavit-ating ram. On the other hand, when the check valve is closed, the restriction to flow from the exhaust manifold to tank is reduced to a minimum and energy is conserved.

Two illustrative embodiments of the invention are described herein with reference to the accompanying drawings in which:

FIG. 1 is a sectional view of a typical parallel circuit directional control valve incorporating one form of the invention.

322,285 Patented Nov. 1, 19%6 FIG. 2 is a sectional view taken on line 2 of FIG. 1. FIG. 3 is a sectional view taken on line 33 of FIG. 1. FIG. 4 is a sectional view of a typical directional control valve of the series-parallel or tandem type incorporating a second form of the invention.

FIG. 5 is a sectional view taken on line 5-5 of FIG. 4. FIG. 6 is a sectional view taken on line 6-6 of FIG. 5. FIG. 7 is a sectional view taken on line 7-7 of FIG. 5. As shown in FIGS. l-3, the invention is embodied in a conventional parallel circuit directional control valve including a housing 11 formed with inlet, exhaust and carryover ports 12, 13 and 14, respectively, and containing three valving units A, B and C of the sliding plunger type. The housing is cored to provide a supply manifold comprising an inlet chamber 15 communicating wit-h inlet port 12 and two parallel branches 16 and 17, a C-s-haped exhaust manifold 18' including two legs 19 and 21, and an open center path including passages 2225 and which leads to the carry-over port 14.

Valving unit A includes a pair of motor chambers 26' and 27, each of which communicates with a service-port (not shown), and a hollow, three-position valve plunger 28 formed with a central annular groove 29 and a pair of lands 31 and 32. Land 31 contains an internal bore that is intersected by two sets of radial passages 33 and 34, and these parts serve selectively to connect motor chamber 26 with the branch 16 of the supply manifold and the leg 19 of the exhaust manifold. Land 32 is provided with a similar bore and sets radial passages 35 and 36 which serve selectively to connect motor chamber 27 with manifold branch 17 and manifold leg 21. Valving units B and C are essentially the same as unit A so their parts are identified by the same reference numerals with the postscripts b and 0 added for clarity.

As shown in FIGS. 2 and 3, housing 11 contains a cored chamber 37 which lies below the exhaust manifold 18 and which opens directly into the two branches 16 and 17 of the supply manifold. This chamber 37 communicates with the manifold 18 through a by-pass passage 38 which is encircled by the valve seat 39 of a by-pass check valve 41. The check valve 41 is biased closed by a coil compression spring 42 and by the pressure in chamber 37 which acts upon its lower face 43, and is urged in the opening direction by the pressure in the exhaust manifold 18 which acts upon the annular area on the upper face of the valve bounded by the seat 39 and the outer periphery of the valve stem 44. In the region of the check valve 41 the exhaust manifold is divided into upper and lower sections 18U and 18L, respectively, by a web 45 which together with the upper part of housing 11, is bored to receive and guide the valve stem 44. The valve stem 44 is formed with intersecting axial and radial passages 46 and 47, respectively, which constitute the sole flow connection between exhaust manifold 18 and exhaust port 13. The radial passages 47 cooperate with the land 48 provided by web 45 to define a variable flow restriction whose flow resistance increases as the check valve moves in the opening direction.

When the directional control valve of FIG. 1 is in use, inlet port 12 is connected with a pump, exhaust port 13' is connected with a tank, carry-over port 14 is connected with a secondary control valve, and the service ports of each of the units A, B and C are connected to the opposite sides of a double-acting ram. With the valve plungers 28, 28b and 28c in their illustrated neutral positions, the three controlled rams are hydraulically locked and the annular grooves 29, 29b and 29c assaaee passes to the secondary control valve where it may be used to effect some auxiliary power function.

When one of the valve plungers is shifted to an operative position, the open center path is closed, thereby terminating the supply of fluid to the carry-over port 14, and the opposite sides of the controlled ram are connected with the supply and exhaust manifolds. If movement of the ram is opposed by the applied load, the pressure in the supply manifold and in chamber 37 will be much higher than the pressure in exhaust manifold 18, and consequently check valve 41 will be closed. Under this condition, the return flow from the ram entering manifold 18 will pass through passages 47 and 46 to the exhaust port 13 and then be conveyed to the tank. Radial passages 47 are so sized that this return flow to tank is not unduly restricted. On the other hand, if the load acts on the ram in the opposite direction and is large enough to cause it to move at a speed with which the pump cannot keep pace, the pressure in the supply manifold and in chamber 37 will decrease below the pressure in manifold 13. At this time check valve 41 will open, and simultaneously land 4-8 will commence to overtravel and restrict radial passages 47. The increased restriction to flow through radial passages 47 increases the backpressure in manifold 18 and causes some of the fluid being returned to manifold 18 to flow through by-pass passage 38 and chamber 37 into the supply manifold. This regenerative flow supplements the fluid being delivered by the pump. Since the distance valve 41 moves in the opening direction depends upon the severity of the cavitation condition and determines the backpressure in manifold 18, the rate of flow of regenerative fluid will always be sufficient to maintain the expanding side of the ram liquid-filled. When the ram again encounters an opposing load, the pressure in the supply manifold will rise and check valve 41 will close. Now all of the fluid being returned to exhaust manifold 18 is again transmitted to tank through exhaust port 13.

Inasmuch as the directional control valve of FIGS. l-3 employs a parallel circuit, several or all of the rams it controls may be operated simultaneously. In the case of multiple ram operation, one or more of the rams may tend to cavitate. However, since the occurrence of such a condition still is reflected as a decrease in the pressure in the supply manifold, the regenerative device of the present invention will combat it in the same way as in the case of a single ram operation.

In the embodiment of FIGS. 47, the invention is embodied in a directional control valve of the series parallel or tandem type. Where practical, the parts of this valve bear the same numerals as their counterparts in FIG. 1, with primes being added for clarity. In this valve, the housing is cored to provide a supply manifold comprising an inlet chamber that communicates with the inlet port 12 and passages 49, 51, 52, 53 and 54. This embodiment has no carry-over port so the supply manifold is adapted to be connected with the exhaust manifold 18 by cored passage 55, and thus serve as an open center unloading path, when the plungers 28 and 28b are in their neutral positions. These valve plungers also are of the three-position, hollow type, but they include central lands 56 and 56b which are flanked by a pair of annular grooves 57 and 58 and 57b and 58b, respectively. The grooves 57 and 58 of plunger 28 complete the supply path to valving unit B when this plunger is in neutral position, but, when it is shifted to one of its operative positions, land 56 and one of the lands 31 and 32' close this path and thus also inherently interrupt the open center unloading path. Similarly, the grooves 575 and 58b of plunger 28b complete the open center unloading path when this plunger is in its neutral position, and its land 56b and one of the lands 31b and 32b interrupt that path when the plunger is shifted to an operative position.

The second embodiment is provided with a cored chamber 37' which is connected with the exhaust manifold 18 through a by-pass passage 38. Since the valving units A and B are connected in a series supply circuit, it is essential that the regenerative flow path be connected with the supply manifold upstream of the first unit in the series if protection against cavitation is to be provided for both valving units. Therefore, as illustrated, chamber 37' is connected with inlet chamber 15 through the cored passage 59. As in the case of the first embodiment, flow through the by-pass passage 38 is controlled by a check valve 41 which is biased closed by a spring 42 and by the pressure in chamber 37', and which is urged in the opening direction by the pressure in exhaust manifold 18'. The stem 44 of valve 41 is guided in a sleeve 61 which is pressed into a bore in housing 11' and which contains two longitudinally spaced sets of radial passages 62 and 63 which, together with two similar sets of passages 64 and 65 formed in the valve stem, constitute a variable restriction in the flow connection between manifold 18 and exhaust port 13'. The check valve 41 is free to rotate in the sleeve 61 and, therefore, as shown in FIGS. 6 and 7, the set of passages 65 is circumferentially offset relative to the set 64 so that flow between the exhaust manifold 18 and port 13 is never cut-off or unduly restricted.

With both of the valve plungers 28' and 26b in the neutral position, the fluid delivered to inlet port 12' by the pump passes to tank through the supply manifold (comprising chamber 15 and passages 49 and 5154), passage 55, manifold 18, passages 62-64, axial passage 46 and exhaust port 13'. At this time, check valve 41 is closed. When plunger 28 is shifted to one of its operative positions, the supply path to valving unit B is closed, fluid under pressure is delivered to one of the motor chambers 26 and 27, and the fluid returning to the other motor chamber from the ram is transmitted to one of the legs 19' and 21' of the exhaust manifold. Under normal loading conditions the pressure in inlet chamber 15 and in chamber 37 will be much higher than the pressure in exhaust manifold 18' and the check valve 41' will remain closed. Therefore, all of the fluid being returned to the exhaust manifold will pass to tank through radial passages 6265, axial passage 46 and exhaust port 13. Under abnormal loading conditions the ram controlled by valving unit A may cavitate, and when this happens, the pressure in chamber 37 decreases below the pressure in exhaust manifold 18. As a result, check valve 41' opens and the restriction to flow through passages 62 and 64 and through passages 63 and 65 increases. Now some of the fluid being returned to the exhaust manifold 18 from the contracting side of the ram is forced into and through the supply manifold to the expanding side of the ram. When normal load conditions are resumed, the check valve 41 closes.

When valve plunger 28' is in its neutral position, the supply path to valving unit B is open and valve plunger 28b may be moved to an operative position to actuate the ram connected with its service ports. In this case, land 56b and one of the lands 31b and 32b close the open center unloading path. The regeneration device provided by the invention serves unit B in the same way it serves unit A so the description of its operation will not be repeated.

It should be noted that in both embodiments of the invention, the travel of the check valve in the opening direction is limited so that the variable restrictor does not create an excessively high backpressure in the exhaust manifold. Because of this, the plunger seals 50 in FIG. 1 and 50' in FIG. 4 may be of the low pressure type. If the lines leading from the directional control valve to the rams are unusually long so that a higher backpressure is required in order to force fluid into the expanding side of the ram, the check valves can be designed to have a greater range of travel. However, in this case, it may be necessary to replace seals 50 and 50 with high pressure seals.

As stated previously, the drawings and description relate merely to two illustrative embodiments of the invention. Since many changes can be made in the structures of these embodiments without departing from the inventive concept, the following claims should provide the sole measure of the scope of the invention.

What we claim is:

1. In a distributing valve of the type including inlet and exhaust ports, a plurality of valving units provided with service ports to which and from which they control the flow of fluid, an exhaust manifold connected with the exhaust port and to which the valving units direct fluid from their service ports, and a supply manifold that directs fluid from the inlet port to the valving units, the improvement which comprises (a) a by-pass passage interconnecting the supply and exhaust manifolds;

(b) a check valve responsive to the pressurev differential between the two manifolds and arranged to permit flow through the by-pass passage from the exhaust manifold to the supply manifold but to block flow in the reverse direction; and

(c) a variable flow restrictor interposed in the connection between the exhaust manifold and the exhaust port and operatively connected with the check valve, the operative connection being so arranged that the degree of restriction afforded by the flow restrictor increases and decreases, respectively, as the check valve opens and closes.

2. In a distributing valve of the type including inlet and exhaust ports, a plurality of valving units provided with service ports to which and from which they control the flow of fluid, an exhaust manifold connected with the exhaust port and to which the valving units direct fluid from their service ports, and a supply manifold that directs fluid from the inlet port to the valving units, the improvement which comprises (a) a by-pass passage interconnecting the supply and exhaust manifolds;

(b) a spring biased check valve normally closing the by-pass passage;

(c) first means responsive to the pressure in the supply manifold urging the check valve in the closing direction;

(d) second means responsive to the pressure in the exhaust manifold urging the check valve in the opening direction; and

(e) a variable flow restrictor interposed in the connection between the exhaust manifold and the exhaust port, the flow restrictor being operatively connected with the check valve so that the restriction it affords increases and decreases, respectively, as the check valve opens and closes.

3. In a distributing valve of the type including inlet and exhaust ports, a plurality of valving units provided with service ports to which and from which they control the flow of fluid, an exhaust manifold connected with the exhaust port and to which the valving units direct fluid from their service ports, and a supply manifold that connects the valving units in series with the inlet port, the

improvement which comprises (a) a bypass passage connecting the exhaust manifold with the supply manifold at a point upstream of the first valving unit in the series;

(b) a check valve responsive to the pressure differential between the two manifolds and arranged to per-t mit flow through the by-pass passage from the exhaust manifold to the supply manifold but to block flow in the reverse direction; and

(c) a variable flow restrictor interposed in the connection between the exhaust manifold and the exhaust port and operatively connected with the check valve, the operative connection being so arranged that the degree of restriction afforded by the flow restrictor increases and decreases, respectively, as the check valve opens and closes.

References Cited by the Examiner UNITED STATES PATENTS 2,499,425 3/1950 Stephens 137-59612 2,980,135 4/1961 Tennis 137"596.12 3,036,597 5/1962 Frantz l37596.12 3,194,265 7/ 1965 Tennis 137-596 M. CARY NELSON, Primary Examiner. H. KLINKSIEK, Examiner. 

1. IN A DISTRIBUTING VALVE OF THE TYPE INCLUDING INLET AND EXHAUST PORTS, A PLURALITY OF VALVING UNITS PROVIDED WITH SERVICE PORTS TO WHICH AND FROM WHICH THEY CONTROL THE FLOW OF FLUID, AN EXHAUST MANIFOLD CONNECTED WITH THE EXHAUST PORT AND TO WHICH THE VALVING UNITS DIRECT FLUID FROM THEIR SERVICE PORTS, AND A SUPPLY MANIFOLD THAT DIRECTS FLUID FROM THE INLET PORT TO THE VALVING UNITS, THE IMPROVEMENT WHICH COMPRISES (A) A BY-PASS PASSAGE INTERCONNECTING THE SUPPLY AND EXHAUST MANIFOLDS; (B) A CHECK VALVE RESPONSIVE TO THE PRESSURE DIFFERENTIAL BETWEEN THE TWO MANIFOLDS AND ARRANGED TO PERMIT FLOW THROUGH THE BY-PASS PASSAGE FROM THE EXHAUST MANIFOLD TO THE SUPPLY MANIFOLD BUT TO BLOCK FLOW IN THE REVERSE DIRECTION; AND (C) A VARIABLE FLOW RESTRICTOR INTERPOSED IN THE CONNECTION BETWEEN THE EXHAUST MANIFOLD AND THE EXHAUST PORT AND OPERATIVELY CONNECTED WITH THE CHECK VALVE, THE OPERATIVE CONNECTION BEING SO ARRANGED THAT THE DEGREE OF RESTRICTION AFFORDED BY THE FLOW RESTRICTOR INCREASES AND DECREASES, RESPECTIVELY, AS THE CHECK VALVE OPENS AND CLOSES. 